Abstract: The valve is susceptible to damage caused by the instantaneous impact of high-pressure hydrogen during operation, resulting in spontaneous ignition of high-pressure hydrogen release. In this paper, an in-house solver is developed within OpenFOAM framework. The Fuller-Schettler-Giddings diffusion coefficient model and 21-step hydrogen/air chemical reaction mechanism is used to describe the diffusion and chemical reaction of spontaneous ignition process. Meanwhile, this paper carries out the numerical study on spontaneous ignition of high-pressure hydrogen release from valve and analyses the influence law of 4~10 MPa release pressures on spontaneous ignition of high-pressure hydrogen release. The critical pressure for spontaneous ignition of high-pressure hydrogen release though a valve is given. The investigation shows that, compared with straight tube leaks, when the high-pressure hydrogen release though a valve, the complex structure inside the valve causes the reflection and bypassing of the leading shock wave, which raises the shock-heated air temperature and promotes the occurrence of spontaneous ignition of high-pressure hydrogen inside the valve. When the release pressure reaches 6 MPa, spontaneous ignition occurs at the center of the valve. In addition, the increase in release pressure increases the likelihood of spontaneous ignition, as the release pressure increases from 6 MPa to 10 MPa, the time required for ignition decreases from 26 μs to 10 μs and the distance required for ignition decreases from 24 mm to 10 mm.

Key words: hydrogen safety, flame, leakage, spontaneous ignition, numerical simulation